This invention relates to air pre-conditioning wherein a portion of the outside air intake is efficiently dehumidified. Heretofore, the desiccants employed have been expensive and because of their nature the dehumidifying section of air conditioning equipment has been fabricated of exceedingly expensive corrosive resistant materials. Accordingly, it is a primary object of this invention to provide a relatively inexpensive and substantially non-corrosive desiccant that is economically effective and which is adapted to use in relatively inexpensive equipment made of commercial grade materials such as protectively treated steel and the like. Cost effective stand-alone installation of a dehumidifier is an object of this invention, all of which is accomplished without change to the downstream refrigeration and/or heating equipment.
It is an object of this invention to employ Glycol as a desiccant and to enhance its moisture absorption capacity by adding to it a Polymer. Suitable soluble compounds from the glycol family are Tri ethylene glycol and/or tetra ethylene glycol, a preferred compound being Polyethyleneglycol. Additives such as Fructose, Silica gel, Alumina silicates, and the like can be included to enhance the liquid carrying capacity of the glycol.
There are a number of polymer materials known to be useful as desiccants to absorb water moisture and to be regenerated for repeated use, it being an object of this invention to enhance a liquid glycol with a liquid polymer, for use as a desiccant. Such polymers which are feasible to be used with glycol desiccants are as follows:
Polystyrene Sulfonic acid lithium salt PA1 Polystyrene sulfonic acid sodium salt PA1 Polyacrylic acid ammonium salt PA1 Poly (methacrylic acid) sodium salt PA1 Poly (n-vinylacetamide vinyl sulfonate) sodium salt PA1 Polyacrylic acid sodium salt PA1 Cellulose sulfonate sodium salt PA1 Methyl cellulose
The preferred desiccant additive is sulfonated Lithium SO.sub.3 Li, PSSALS in a solution and at a viscosity that can be pumped and sprayed with a heat range of 80.degree. F. to 225.degree. F. db. The sorption properties of this Lithium polymer salt solution is enhanced 4% to 15% of weight fraction gain by adding it to Tri ethylene glycol (TEG) 10% (by weight). In practice, the improved performance is greater than the algebraic addition prediction for the mixture. And, it is clear that the moisture absorption capacity of the TEG- PSSALS mixture is far superior as it produces unexpected results when compared with known prior art desiccants.
It is a liquid glycol desiccant enhanced with a liquid polymer material with which this invention is particularly concerned, and to this end it is an object to provide the same in the form of an improved hygroscepic desiccant fluid.
Water vapor sorption by polymers is a recognized advantage, the water uptake capability being most important. Ion-dipole interaction is to be considered, reference being made to FIGS. 3a, 3b and 3c of the drawings, which illustrate the comparisons between the use of Lithium, Sodium and Potassium. It becomes apparent that the Lithium ion Li+ accommodates a far greater amount of water of the three, due to its small cationic size as compared with either Sodium Na+ of Potassium K+. The atomic weight and corresponding cationic size of various elements are to be considered as follows:
______________________________________ Li Lithium 6.9 Na Sodium 23 K Potassium 39 Ca Calcium 40 Cs Cesium 133 ______________________________________
Therefore, is it an object of this invention to employ the better of the known salts in the sulfonation of the aforementioned polymers employed as a hygrosopic liquid, especially as a desiccant additive to glycol. Accordingly, Polystyrene Sulfonate Acid Lithium Salt solution or PSSALS is the preferred embodiment use herein (see FIG. 7).
Air conditioning involves generally, an outside air supply, a supply air discharge into a building interior, return air intake from the building interior, and a relief air discharge. The polymer enhanced glycol solution air pre-conditioner of the present invention is adapted to the outside air intake of the existent air conditioning equipment. It is an object of this invention to advantageously employ a portion of the outside supply air intake for desiccant treatment. It is also an object of this invention to advantageously employ a heat-pipe to extract heat after dehumidification and to dissipate that heat. The air dehumidifier intake section herein disclosed replaces an air intake or power section of usual equipment and is preferably attached to a blower section unit that separates the relief air from the return air, as shown.
An air conditioning system involves the discharge of relief air that is replaced by outside supply air. The volume ratio of these two columns of air varies as a result of variations leakage from the conditioned air space involved, the relief air being stale interior air retrieved at a place or places of higher interior temperature and where stale air exists. Consequently, relief air is substantially warmer than supply air (the conditioned air), it being an object of this invention to advantageously employ warmer relief air before its discharge as exhaust air, by dissipating its usable heat energy through a heat exchanger into outside air. It is still another object of this invention to advantageously employ the heat energy rejected by the heat-pipe, as will be described.
It is an object of this invention to directly process the weakened higher viscosity desiccant through a multi-effect reflux boiler concentrator, using the direct application of heat with a counter flow of desiccant from which water vapor is driven out of the weakened water saturated liquid and desiccant enriched vapor is condensed and returned to the contactor section or sections as strengthened desiccant.
It is an object of this invention to control the temperature of liquid refrigerant returned to the refrigeration compressor, so that compressor capacity is maximized. In practice, this is accomplished with a heat exchanger that desuperheats and condenses the refrigerant vapor, and simultaneously recovers heat from recirculated glycol or polymer enhanced glycol which is then distributed to a spray header and moisture extracted by heated exhaust air.
It is also an object of this invention to efficiently regenerate the-glycol-polymer enhanced desiccant solution (a mixture), a portion of which could be lost as a result of vaporization, by providing a reflux boiler to enrich the desiccant by condensing the glycol vapors and avoiding their loss.
It is still another object of this invention to implement heat-pipes so as to function as a dehumidification contacter (heat in) and to function as a regeneration (heat out) heat source for reconstituting a strong desiccant mixture of glycol based polymer enhanced desiccant. The heat in ends of the heat-pipes operate in the incoming outside air OSA, while the heat out ends of the heat-pipes operate in the outgoing relief air RE, there being heater means to raise the relief air to an effective regenerative temperature. Additionally, the heat of condensation from the dehumidification process is recovered for desiccant regeneration, and the AC heat of compression is also recovered for desiccant regeneration.